As a result of technological advances such as the fax-modem, it has become common to send and receive facsimile ("fax") documents with personal computers rather than with dedicated fax machines. The use of computers to communicate and display faxed documents has many advantages over the use of dedicated fax machines, such as facilitating the editing of faxed documents. However, the quality of text tends to degrade when a faxed document is displayed on a computer monitor. This degradation occurs primarily because the spatial resolution of most computer monitors is much lower than that of most printed faxes. Current printed fax technology can provide a resolution of 1728 pixels by 2376 pixels for A4 size paper. In contrast, currently available high-quality computer monitors generally cannot provide a resolution greater than about 1280 by 1000 pixels, and some less expensive computer monitors cannot provide a resolution greater than 640 by 480 pixels. A similar loss in quality also tends to occur when a scanned document is displayed on a computer monitor, for essentially the same reason. One common result of some resolution reduction methods is that text appears to be out of focus, or "washed out".
A good method of displaying text images at low resolution is essential to any software package designed to display scanned or faxed images on a monitor. One way to produce more readable documents on screen is to utilize optical character recognition (OCR) products to reproduce text on screen. For many reasons, however, it may be desirable to avoid performing OCR. It is therefore desirable to perform resolution reduction on scanned or faxed documents for display on a computer monitor in a manner that reduces or eliminates degradation in image quality, particularly with respect to text images.
For purposes of editing a scanned or faxed document, it may be desirable to view the entire document on the monitor at one time. A person who is editing the layout of a page for publication, for example, may need to view the entire page at once in order to work efficiently. One problem associated with existing display software, however, is that due to the change in resolution, the entire document generally cannot be displayed on the monitor at once while still maintaining adequate readability. While portions of a displayed page can be magnified to provide greater readability, the remaining portions of the page are generally hidden from view. Although the page can be reduced in size in order to fit the page to the screen, the text often becomes too small to read. Consequently, a person editing the document may be required to scroll up and down the displayed document repeatedly, which can be annoying and time consuming.
Hence, it would be desirable to have a technique for improving the quality of display on a computer monitor of scanned or faxed documents. In particular, it would be desirable to have a technique for increasing the readability of text in scanned or faxed documents when displayed on a monitor, and for facilitating the editing of such documents.